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authorZheng Liu <wenqing.lz@taobao.com>2014-09-01 22:26:49 -0400
committerTheodore Ts'o <tytso@mit.edu>2014-09-01 22:26:49 -0400
commiteb68d0e2fc5a4e5c06324ea5f485fccbae626d05 (patch)
tree2615b7518bebee73f197efbf32df9b4b21f9969e /fs/ext4/extents_status.c
parente963bb1de415ab06693357336c1bec664753e1e2 (diff)
ext4: track extent status tree shrinker delay statictics
This commit adds some statictics in extent status tree shrinker. The purpose to add these is that we want to collect more details when we encounter a stall caused by extent status tree shrinker. Here we count the following statictics: stats: the number of all objects on all extent status trees the number of reclaimable objects on lru list cache hits/misses the last sorted interval the number of inodes on lru list average: scan time for shrinking some objects the number of shrunk objects maximum: the inode that has max nr. of objects on lru list the maximum scan time for shrinking some objects The output looks like below: $ cat /proc/fs/ext4/sda1/es_shrinker_info stats: 28228 objects 6341 reclaimable objects 5281/631 cache hits/misses 586 ms last sorted interval 250 inodes on lru list average: 153 us scan time 128 shrunk objects maximum: 255 inode (255 objects, 198 reclaimable) 125723 us max scan time If the lru list has never been sorted, the following line will not be printed: 586ms last sorted interval If there is an empty lru list, the following lines also will not be printed: 250 inodes on lru list ... maximum: 255 inode (255 objects, 198 reclaimable) 0 us max scan time Meanwhile in this commit a new trace point is defined to print some details in __ext4_es_shrink(). Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Jan Kara <jack@suse.cz> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4/extents_status.c')
-rw-r--r--fs/ext4/extents_status.c186
1 files changed, 176 insertions, 10 deletions
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 95da65c60d83..09fd57667262 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -11,6 +11,8 @@
*/
#include <linux/rbtree.h>
#include <linux/list_sort.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
#include "ext4.h"
#include "extents_status.h"
@@ -313,19 +315,27 @@ ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len,
*/
if (!ext4_es_is_delayed(es)) {
EXT4_I(inode)->i_es_lru_nr++;
- percpu_counter_inc(&EXT4_SB(inode->i_sb)->s_extent_cache_cnt);
+ percpu_counter_inc(&EXT4_SB(inode->i_sb)->
+ s_es_stats.es_stats_lru_cnt);
}
+ EXT4_I(inode)->i_es_all_nr++;
+ percpu_counter_inc(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);
+
return es;
}
static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
{
+ EXT4_I(inode)->i_es_all_nr--;
+ percpu_counter_dec(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);
+
/* Decrease the lru counter when this es is not delayed */
if (!ext4_es_is_delayed(es)) {
BUG_ON(EXT4_I(inode)->i_es_lru_nr == 0);
EXT4_I(inode)->i_es_lru_nr--;
- percpu_counter_dec(&EXT4_SB(inode->i_sb)->s_extent_cache_cnt);
+ percpu_counter_dec(&EXT4_SB(inode->i_sb)->
+ s_es_stats.es_stats_lru_cnt);
}
kmem_cache_free(ext4_es_cachep, es);
@@ -729,6 +739,7 @@ int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
struct extent_status *es)
{
struct ext4_es_tree *tree;
+ struct ext4_es_stats *stats;
struct extent_status *es1 = NULL;
struct rb_node *node;
int found = 0;
@@ -765,11 +776,15 @@ int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
}
out:
+ stats = &EXT4_SB(inode->i_sb)->s_es_stats;
if (found) {
BUG_ON(!es1);
es->es_lblk = es1->es_lblk;
es->es_len = es1->es_len;
es->es_pblk = es1->es_pblk;
+ stats->es_stats_cache_hits++;
+ } else {
+ stats->es_stats_cache_misses++;
}
read_unlock(&EXT4_I(inode)->i_es_lock);
@@ -931,11 +946,16 @@ static int __ext4_es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
struct ext4_inode_info *locked_ei)
{
struct ext4_inode_info *ei;
+ struct ext4_es_stats *es_stats;
struct list_head *cur, *tmp;
LIST_HEAD(skipped);
+ ktime_t start_time;
+ u64 scan_time;
int nr_shrunk = 0;
int retried = 0, skip_precached = 1, nr_skipped = 0;
+ es_stats = &sbi->s_es_stats;
+ start_time = ktime_get();
spin_lock(&sbi->s_es_lru_lock);
retry:
@@ -946,7 +966,8 @@ retry:
* If we have already reclaimed all extents from extent
* status tree, just stop the loop immediately.
*/
- if (percpu_counter_read_positive(&sbi->s_extent_cache_cnt) == 0)
+ if (percpu_counter_read_positive(
+ &es_stats->es_stats_lru_cnt) == 0)
break;
ei = list_entry(cur, struct ext4_inode_info, i_es_lru);
@@ -956,7 +977,7 @@ retry:
* time. Normally we try hard to avoid shrinking
* precached inodes, but we will as a last resort.
*/
- if ((sbi->s_es_last_sorted < ei->i_touch_when) ||
+ if ((es_stats->es_stats_last_sorted < ei->i_touch_when) ||
(skip_precached && ext4_test_inode_state(&ei->vfs_inode,
EXT4_STATE_EXT_PRECACHED))) {
nr_skipped++;
@@ -990,7 +1011,7 @@ retry:
if ((nr_shrunk == 0) && nr_skipped && !retried) {
retried++;
list_sort(NULL, &sbi->s_es_lru, ext4_inode_touch_time_cmp);
- sbi->s_es_last_sorted = jiffies;
+ es_stats->es_stats_last_sorted = jiffies;
ei = list_first_entry(&sbi->s_es_lru, struct ext4_inode_info,
i_es_lru);
/*
@@ -1008,6 +1029,22 @@ retry:
if (locked_ei && nr_shrunk == 0)
nr_shrunk = __es_try_to_reclaim_extents(locked_ei, nr_to_scan);
+ scan_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
+ if (likely(es_stats->es_stats_scan_time))
+ es_stats->es_stats_scan_time = (scan_time +
+ es_stats->es_stats_scan_time*3) / 4;
+ else
+ es_stats->es_stats_scan_time = scan_time;
+ if (scan_time > es_stats->es_stats_max_scan_time)
+ es_stats->es_stats_max_scan_time = scan_time;
+ if (likely(es_stats->es_stats_shrunk))
+ es_stats->es_stats_shrunk = (nr_shrunk +
+ es_stats->es_stats_shrunk*3) / 4;
+ else
+ es_stats->es_stats_shrunk = nr_shrunk;
+
+ trace_ext4_es_shrink(sbi->s_sb, nr_shrunk, scan_time, skip_precached,
+ nr_skipped, retried);
return nr_shrunk;
}
@@ -1018,7 +1055,7 @@ static unsigned long ext4_es_count(struct shrinker *shrink,
struct ext4_sb_info *sbi;
sbi = container_of(shrink, struct ext4_sb_info, s_es_shrinker);
- nr = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
+ nr = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_lru_cnt);
trace_ext4_es_shrink_count(sbi->s_sb, sc->nr_to_scan, nr);
return nr;
}
@@ -1031,7 +1068,7 @@ static unsigned long ext4_es_scan(struct shrinker *shrink,
int nr_to_scan = sc->nr_to_scan;
int ret, nr_shrunk;
- ret = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
+ ret = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_lru_cnt);
trace_ext4_es_shrink_scan_enter(sbi->s_sb, nr_to_scan, ret);
if (!nr_to_scan)
@@ -1043,19 +1080,148 @@ static unsigned long ext4_es_scan(struct shrinker *shrink,
return nr_shrunk;
}
-void ext4_es_register_shrinker(struct ext4_sb_info *sbi)
+static void *ext4_es_seq_shrinker_info_start(struct seq_file *seq, loff_t *pos)
+{
+ return *pos ? NULL : SEQ_START_TOKEN;
+}
+
+static void *
+ext4_es_seq_shrinker_info_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+ return NULL;
+}
+
+static int ext4_es_seq_shrinker_info_show(struct seq_file *seq, void *v)
+{
+ struct ext4_sb_info *sbi = seq->private;
+ struct ext4_es_stats *es_stats = &sbi->s_es_stats;
+ struct ext4_inode_info *ei, *max = NULL;
+ unsigned int inode_cnt = 0;
+
+ if (v != SEQ_START_TOKEN)
+ return 0;
+
+ /* here we just find an inode that has the max nr. of objects */
+ spin_lock(&sbi->s_es_lru_lock);
+ list_for_each_entry(ei, &sbi->s_es_lru, i_es_lru) {
+ inode_cnt++;
+ if (max && max->i_es_all_nr < ei->i_es_all_nr)
+ max = ei;
+ else if (!max)
+ max = ei;
+ }
+ spin_unlock(&sbi->s_es_lru_lock);
+
+ seq_printf(seq, "stats:\n %lld objects\n %lld reclaimable objects\n",
+ percpu_counter_sum_positive(&es_stats->es_stats_all_cnt),
+ percpu_counter_sum_positive(&es_stats->es_stats_lru_cnt));
+ seq_printf(seq, " %lu/%lu cache hits/misses\n",
+ es_stats->es_stats_cache_hits,
+ es_stats->es_stats_cache_misses);
+ if (es_stats->es_stats_last_sorted != 0)
+ seq_printf(seq, " %u ms last sorted interval\n",
+ jiffies_to_msecs(jiffies -
+ es_stats->es_stats_last_sorted));
+ if (inode_cnt)
+ seq_printf(seq, " %d inodes on lru list\n", inode_cnt);
+
+ seq_printf(seq, "average:\n %llu us scan time\n",
+ div_u64(es_stats->es_stats_scan_time, 1000));
+ seq_printf(seq, " %lu shrunk objects\n", es_stats->es_stats_shrunk);
+ if (inode_cnt)
+ seq_printf(seq,
+ "maximum:\n %lu inode (%u objects, %u reclaimable)\n"
+ " %llu us max scan time\n",
+ max->vfs_inode.i_ino, max->i_es_all_nr, max->i_es_lru_nr,
+ div_u64(es_stats->es_stats_max_scan_time, 1000));
+
+ return 0;
+}
+
+static void ext4_es_seq_shrinker_info_stop(struct seq_file *seq, void *v)
+{
+}
+
+static const struct seq_operations ext4_es_seq_shrinker_info_ops = {
+ .start = ext4_es_seq_shrinker_info_start,
+ .next = ext4_es_seq_shrinker_info_next,
+ .stop = ext4_es_seq_shrinker_info_stop,
+ .show = ext4_es_seq_shrinker_info_show,
+};
+
+static int
+ext4_es_seq_shrinker_info_open(struct inode *inode, struct file *file)
+{
+ int ret;
+
+ ret = seq_open(file, &ext4_es_seq_shrinker_info_ops);
+ if (!ret) {
+ struct seq_file *m = file->private_data;
+ m->private = PDE_DATA(inode);
+ }
+
+ return ret;
+}
+
+static int
+ext4_es_seq_shrinker_info_release(struct inode *inode, struct file *file)
+{
+ return seq_release(inode, file);
+}
+
+static const struct file_operations ext4_es_seq_shrinker_info_fops = {
+ .owner = THIS_MODULE,
+ .open = ext4_es_seq_shrinker_info_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = ext4_es_seq_shrinker_info_release,
+};
+
+int ext4_es_register_shrinker(struct ext4_sb_info *sbi)
{
+ int err;
+
INIT_LIST_HEAD(&sbi->s_es_lru);
spin_lock_init(&sbi->s_es_lru_lock);
- sbi->s_es_last_sorted = 0;
+ sbi->s_es_stats.es_stats_last_sorted = 0;
+ sbi->s_es_stats.es_stats_shrunk = 0;
+ sbi->s_es_stats.es_stats_cache_hits = 0;
+ sbi->s_es_stats.es_stats_cache_misses = 0;
+ sbi->s_es_stats.es_stats_scan_time = 0;
+ sbi->s_es_stats.es_stats_max_scan_time = 0;
+ err = percpu_counter_init(&sbi->s_es_stats.es_stats_all_cnt, 0);
+ if (err)
+ return err;
+ err = percpu_counter_init(&sbi->s_es_stats.es_stats_lru_cnt, 0);
+ if (err)
+ goto err1;
+
sbi->s_es_shrinker.scan_objects = ext4_es_scan;
sbi->s_es_shrinker.count_objects = ext4_es_count;
sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;
- register_shrinker(&sbi->s_es_shrinker);
+ err = register_shrinker(&sbi->s_es_shrinker);
+ if (err)
+ goto err2;
+
+ if (sbi->s_proc)
+ proc_create_data("es_shrinker_info", S_IRUGO, sbi->s_proc,
+ &ext4_es_seq_shrinker_info_fops, sbi);
+
+ return 0;
+
+err2:
+ percpu_counter_destroy(&sbi->s_es_stats.es_stats_lru_cnt);
+err1:
+ percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
+ return err;
}
void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi)
{
+ if (sbi->s_proc)
+ remove_proc_entry("es_shrinker_info", sbi->s_proc);
+ percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
+ percpu_counter_destroy(&sbi->s_es_stats.es_stats_lru_cnt);
unregister_shrinker(&sbi->s_es_shrinker);
}